A multitude of solutions is available for call forwarding. German patent reference DE 100 59 327, for example, appears to describe a device and a method for forwarding messages to terminals of different communications media, in order to achieve the ability to reach a subscriber in a switch between a plurality of terminals, including both fixed and mobile terminals. Among the mobile terminals are mobile telephones as well. The reference involves a telecommunications device having a database, which includes subscriber-specific information about the number of target subscribers and terminals assigned thereto, and message formats compatible with these terminals. The control of the processes is implemented via a corresponding control device. Upon receipt of a message for a target subscriber, the control device utilizes the subscriber-specific information to select one or a plurality of terminal(s) via which the target subscriber is able to be reached, converts the message with the aid of conversion modules, and forwards it to the selected terminals for transmission.
In this approach, calls from the fixed network as well as calls from the mobile radio communications network are forwarded to the terminals specified by the subscriber-specific information.
This approach focuses on the ability of reaching the subscriber during a switch between a plurality of terminals that may be of different type. Savings in connection with the fees of network interworking or costs resulting from the rate structures of the communication networks themselves, are not the subject of the solution.
German patent reference DE 199 15 548 A1 describes a method for combining fixed network and mobile communications network telephony. This solution appears based on at least one home location source, a fixed network, and a mobile telephony network. The subscriber has a dual-mode terminal, which operates both in radio network operation and in cordless mode. The subscriber can be reached and respond at one number, via a single terminal having automatic network selection.
In addition, German patent reference DE 198 10 797 appears to describe a network-crossing mobility management for multi-range terminals. To control the network-crossing reachability of a multi-range terminal having a mobile line and a fixed network line, the multi-range terminal transmits to the mobile radio communications network a mobile-network cancellation message when entering the service area of the fixed network, or a mobile-network inscription message when leaving it. In the home location register of the mobile radio communications network, this sets, or cancels, reachability information that indicates the reachability of the multi-range terminal on the fixed network. In a connection request, a query to the home location register takes place. Depending on the reachability information, the call is routed to the mobile radio network or to the fixed network line of the multi-range terminal.
In this approach, calls from the fixed network and calls from the mobile radio network are both forwarded as a function of reachability information. Here, too, the focus is not on network interworking fees or network rates.
German patent reference DE 102 15 318 A1 appears to describe a method and a device for coupling mobile radio communications technology and fixed network communications technology, a mobile radio terminal dialing an add-on device integrated in the fixed network via a mobile communications network and checking the access authorization of the caller. If the result of the access authorization is positive, line enabling and thus release of a fixed network line takes place. The desired subscriber telephone number is then input from the radio communications network, from the mobile radio communication device directly, or indirectly via an add-on device, and dialed by the add-on device.
This is designed for telephone calls from the mobile radio communications network to the fixed network and is meant to allow the utilization of advantageous mobile radio communications rates as well as fixed network rates.
German patent reference DE 198 56 269 A1 appears to describe a method for call forwarding of a call made from a first subscriber station to a second subscriber station in the public network. The telephone number of the first subscriber station, or a corresponding identification, is transmitted to the second subscriber station where it is routed to a call forwarding memory. With the aid of a call service or data service, the telephone number or the corresponding identification and/or a callback message are/is forwarded to a call service subscriber or a call forwarding location assigned to the second subscriber station as a function of a target address stored in the call forwarding memory. After receipt of the telephone number identification, the call service subscriber may decide whether to return the call of the calling subscriber station.
Only the telephone number or the caller identification is forwarded in this approach. A connection that is subject to a fee is not established at this stage. No automatic additional fees for redirecting the call arise.
It is up to the called subscriber to decide whether he wants to provide the calling subscriber with a callback message or whether he will return the call of the calling subscriber.
All solutions have in common that they actually save money. However, they do not explicitly focus on saving network interworking fees within the sense of the approach according to the present invention.